(1) Field of the Invention
The present invention relates to a fuel tank mainly used for automobiles, more particularly to a construction of a fuel tank for preventing fuel from discharging into the atmosphere when the tank is being filled.
(2) Description of the Related Art
When refueling a vehicle driven by an internal combustion engine, such as a gasoline engine, one uncaps the fuel inlet of the fuel tank and inserts a fuel feed nozzle. However, when the fuel in the tank is low, there is a large quantity of pressurized fuel vapor in space above the liquid surface of the fuel. When the cap is removed, the fuel vapor in the tank escapes to pollute the outside air. Also, while the liquid fuel is filled into the fuel tank, it strikes the fuel within the tank, creating bubbles which again escape to pollute the outside air.
U.S. Pat. No. 3,884,204 and U.S. Pat. No. 3,907,153 disclose an apparatus in which a blowhole is arranged adjacent to an inlet of a fuel feed port so that the fuel vapor is guided to a canister from the blowhole and thus prevented from escaping outside.
In the above known apparatus, however, when the fuel is actually filled into the tank, it flows against the flow of the fuel vapor in the tank and prevents the fuel vapor from being properly drawn out to the canister. As a result, the fuel arrives back at the fuel inlet before it completely fills the tank, thus actuating an automatic shut-down mechanism for fuel feed and preventing satisfactory fueling.
Further, in a fuel tank with a blowhole directly mounted on the tank body, since the fuel inlet is closed, negative pressure is generated within the fuel supply pipe. This promotes bubbling of the fuel. The automatic shut-down mechanism of the fuel feed nozzle is covered with the above bubbles and thus actuates. Consequently, the refueling is not accomplished satisfactorily.